This invention relates generally to vehicle headlamps and particularly to those employing discharge lamp bulbs as light sources. More particularly, the invention deals with a vehicle headlamp system having provisions for aiming a headlamp assembly, comprising a discharge lamp bulb and a reflector, both horizontally and vertically and retaining the same in the proper position with respect to a lamp housing. Still more particularly, the invention pertains to such an aimable vehicle headlamp system featuring improved electrical connection between the discharge lamp assembly and an electric lighting circuit assembly.
Discharge lamps, notably including metallic halide lamps, are finding ever increasing acceptance as light sources of vehicular headlamps. There has, however, been a problem left unsolved in use of discharge lamps for vehicular headlamp applications. The discharge lamp units of a headlamp system need electric lighting circuits including a voltage booster. Connected to the battery that is customarily mounted on the motor vehicle, the booster provides a high voltage required for each discharge lamp bulb to glow by an electric discharge between the pair of electrodes opposed to each other within the bulb.
Conventionally, the lighting circuits have been positioned away from the aimable discharge lamp assemblies. Elongate cables have been used for electrically connecting the lighting circuits to the lamp assemblies.
The present applicant objects to such conventional placement of the lighting circuits and to the use of the elongate cables that conduct currents at high voltages. While servicing the motor vehicle, the operator has been easy to be struck by electricity as the high voltage conductors and other parts of the circuits have been readily accessible. Moreover, the elongate cables have been very easy to produce electric noise. Such sources of noise production should be reduced to an absolute minimum, as today's vehicles, passenger cars in particular, are being furnished with an increasing number of electronic appliances.
For all these reasons there have been strong demands from the automobile industry for the advent of headlamp systems that employ discharge lamps with minimum lengths of high voltage supply cables.